Hi all,
I poured the oven insulated base this past weekend. I used vermiculite, mixed with portland
cement, 5:1 ratio. ( I did not skimp on the cement, I was even a little generous) i checked the
base a couple of days later, seemed a little soft, spongy. I have not worked with vermiculite
before, maybe I am just used to cement and its firmness. Thoughts ? Oh I should say I dry
mixed the vermiculit and cement, and then added water gently.

This weekend I am planning on assembling the oven, my plan is to use refractory cement on the
joints, lay about 2 inches of vermiculite on the oven, blanket wrap the oven, chicken wire &rebar,
and another 4 inches of vermiculite. Of course I am not going to do this all in one shot, it would be over a few days.

I did print and read one of the intallation manuals on line here, I am going to re-read tonight.

Anthony

SpringJim

07-17-2008 03:02 PM

Re: Thoughts ?

Anthony, the vermiculite/perlite layer tends to be a bit "spongy" kind of like styrofoam to me.....and I think the less portland (or less well mixed), the more fragile the material tends to be.

nissanneill

07-17-2008 10:26 PM

Re: Thoughts ?

Hi Jukenut
the vermiculite cement is more like a cork consistency but will harden up a little more over time. I certainly would not put any more Portland cement into the mix as the insulasting effects are reduced as the portland works more like a heat soak than insulating. The 1:5 ratio is exactly as I did mine with no problems.